Right plant, wrong place. I spotted the rosettes of five Ornopordum acanthum self-seeded behind one of the buildings at the music school. Not a prominent spot for this tall, architectural biennial which is worthy of a place in any herbaceous border. Sometimes called the Scotch Thistle or the Cotton Thistle it can grow up to three metres with vivid purple thistle-like flower heads.

 So I carefully dug them up, teasing the tap root out of the soil and replanted them in a mixed border among ornamental grasses. I notice the Beth Chatto nursery is selling O. acanthum at £10.90 a pot so that would be fifty quid's worth!